A method in which a substrate and a film are bonded together by being pressurized in the direction of thickness under heat is known in the prior art as a method of laminating a resist film onto a printed board. According to this method, the adhesion of the film to the substrate is enhanced due to pressurization and a reduction in the viscosity of the film caused by heating, and the quality of covering irregularities is enhanced such that air bubbles are not introduced between the substrate and film when irregularities on the substrate are covered.
However, the heating conditions in this method are limited depending on the substrate and film substances, and thus in cases when enough heat cannot be applied to sufficiently reduce the viscosity of the film, it is difficult to obtain a sufficient degree of lamination efficiency. Particularly when a film contains an active substance, limitations upon the heating temperature and heating time period are severe, as a result of which adhesion of the film to the substrate and quality of covering irregularity on the substrate tend to be insufficient. Further, during actual operations the substrate or lamination apparatus must be preheated to a predetermined temperature in order to attain the aforementioned heating effect, and as a result the deterioration of substrate or film may occur.
Hence, in order to solve these problems, a lamination method and apparatus in which the film does not necessarily have to be heated has been investigated. For example, Japanese Patent Application Laid-Open No. S55-148486 discloses a film lamination apparatus in which a pressurizing device is caused to oscillate along the direction of lamination between the substrate and film. Japanese Patent Application Laid-Open No. S62-60645 discloses a lamination apparatus in which air enclosed between the substrate and film is removed by causing a lamination roller to oscillate by means of an electromagnetic vibrator or the like.